blackWhen creating a dataset for the offline evaluation of a recommender system, the users' feedback can be collected not only blackfrom interactions with items suggested by the deployed recommendation system but also through other modalities such as blackinteractions occurring when browsing the items' catalogue or when following links to sponsored items. It is not straightforward to distinguish the source of the users' feedback blacksince no public datasets provide sufficient data to establish the sources of the users' feedback. Hence, in this paper we focus our investigation on the main source of user's feedback, namely the deployed system [1]}, [2]}, [3]}, [4]}.  In order to blackdemonstrate the Simpson's paradox in recommendation systems, we need a causal hypothesis similar to Hypothesis REF  in Section .
